Central Coast staff present ranch‑level A‑minus‑R calculations and groundwater dashboard showing extensive nitrate exceedances
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Summary
Central Coast Water Board staff showed how ranch‑level applied‑minus‑removed calculations are computed, introduced an interactive groundwater dashboard and maps, and highlighted high percentages of domestic‑well nitrate exceedances in agriculture areas; staff asked the panel to weigh in on discount/credit factors in the A‑minus‑R formula.
Central Coast Water Board staff presented a technical briefing to the State Water Resources Control Board expert panel on Oct. 31 showing how the Central Coast region calculates ranch‑level nitrogen discharge and how those numbers relate to groundwater data. The staff presentation focused on parameters used in the A‑minus‑R (applied minus removed) compliance formula and the evidence behind credits and discount factors the panel was asked to evaluate.
Elaine Saul (Central Coast Water Board) walked panelists through an illustrative ranch example and explained inputs counted in the "applied" side (fertilizer, compost, organic fertilizers, irrigation water) and the removal side (harvest removal, sequestration, scavenging from cover crops and woody amendments). Saul noted that some discount and credit factors remain under review by the State Water Board and are specifically included in panel Question 7 for review.
Why it matters: The Central Coast presentation ties farm‑level reporting to regional groundwater health. Staff previewed a Microsoft Power BI groundwater dashboard and maps that overlay grower‑reported A‑minus‑R values with aquifer risk mapping and well concentrations to help the panel identify where reductions in nitrogen discharge would most likely protect drinking water wells.
Central Coast staff also highlighted a recent fact sheet and groundwater analyses that indicate high nitrate concentrations in many agricultural basins. "For most all groundwater basins, well, actually for all of them, there are significant exceedances," Elaine Saul said, pointing to tabulated exceedance rates and trend analyses that show more wells with increasing nitrate than with decreasing trends.
Panelists discussed how the Central Coast aggregates crop‑level reporting into ranch‑level A‑minus‑R, supports small diversified farms with simplified reporting forms, and relies on third‑party implementers and cooperative extension for outreach in multiple languages. Staff said third‑party programs are funded by member fees and that Water Board staff time is covered by state funds and grower fees.
What’s next: Central Coast staff will provide the dashboard and additional maps to the panel and public. The panel will be asked to advise on the scientific basis for discount factors and whether certain credit/discount elements should be included in A‑minus‑R calculations for regulatory compliance.
Ending: The technical materials and dashboard are slated to be available on the Central Coast Water Board website and will be used by the panel in drafting recommendations on metrics and methods to measure progress toward groundwater protection.
